1. Field of the Invention
The invention is concerned with a rotation granulator for granulating, agglomerating, mixing and drying products of the pharmaceutical and chemical industry, of the food industry, and of agriculture.
2. Background of the Prior Art
Rotation granulators are particularly suitable for the manufacture of spherical items. Unmixed powdery substances are processed and given a spherical shape, due to the action of the rotation-air-injection producing homogeneous concentrated masses. The resulting substances may also be desiccated in the same installation.
In the apparatus known up to this time, the powder is injected from above into the central portion of the rotor-granulator. This is not altogether satisfactory because the injected powder moves slowly from the central portion of the rotary table, and a strong low-pressure area forms in that region. This entails the formation of lumps which have to be dissolved, thus delaying the processing operation.
In addition, the performance of the known apparatus is limited by the filtering system connected at the outlet side. Typically, the filters have to be cleaned, at certain time intervals, in order to remove the small particles that are pulled along by the indraft and deposited there. Since that is done by means of blowing those particles back onto the filters, it becomes necessary to shut-down the installation.
The known devices also have the added disadvantage that the air supply, which enters the granulation container from below, and which is sucked in along the circumference of the rotary table on the inside wall of the container, cannot be controlled at all, or cannot be controlled in a satisfactory manner.
An additional disadvantage of the known installations arises from the devices for the taking of samples; those devices are not well suited to leave the flow conditions in the rotor-granulator part unaffected, inasmuch as, during the taking of samples, there will always be a connection with the ambient atmosphere. Such a connection has an unfavorable effect on the low-pressure area and, thereby, on the flow in the granulator part.